In known devices of this type, the closure means are constituted by a plug and the de-scaling opening is adapted to permit the introduction of a tool within the vaporization chamber. The user can thus, with the aid for example of a screwdriver, scrape the walls of the vaporization chamber so as to achieve mechanical de-scaling. The drawback of these devices resides in the fact that the user, not seeing the calcified deposit within the chamber, scrapes hard and randomly and so does not cover all the surface of the chamber, and particularly the forward portion of said chamber which is the least accessible. Scaling is therefore incomplete. Moreover, he scores the internal surface of the chamber which is generally provided with a cemented coating to improve vaporization, thus destroying the coating. On the other hand, between each de-scaling operation and during the different thermal cycles, the small calcified scales come loose and pass into the distribution chamber, eventually blocking the distribution openings.